Swivel shock absorbing means for shovel booms



R. J. DARRAH April 10, 1934.

SWIVEL SHOQKJLBSQBBING MEANS FOR SHOVEL BOOMS Patented Apr. 10, 1934 SWIVEL SHOCK ABSORBING MEANS FOR SHOVEL BOOMS Robert J. Darrah, Milwaukee, Wis., assignor to Koehring Company, Milwaukee, Wis., a corporation Application December 26, 1930, Serial No. 504,954

2 Claims.

This invention has to do with excavating machines of the type commonly known as shovel cranes or power shovels, wherein there is employed a shovel boom and dipper means mounted on the boom and operated from the power plant carried on the body of the crane.

The ordinary operation of cranes of this type contemplates an excavating movement of the dipper or shovel member usually involving elevating action thereof as it is crowded to its work, a lateral swinging or sweeping of the dipper and its handle by which it is connected with the boom to bring it to an unloading position over a vehicle or a place on which the contents of the dipper may be dumped, and a subsequent restoration of the dipper by reverse operations to bring it back to its excavating position. It is well known that with the usual type of supporting boom, dipper, and dipper stick or handle constructions, a rigid mounting of the boom upon the crane is usually provided. The dipper stick either straddles the supporting boom therefor, or passes between spaced parts of such boom and the usual constructions. The stick forms a long lever, and the operations of the crane usually are such that the car or body of the crane turns to swing the boom and. dipper instrumentalities. Considerable momentum of these parts is created in their movement. The ordinary operation of the machine, furthermore, for eiiiciency, requires rather sudden stopping of the boom movement for swinging, this being true both when the dipper is loaded and when it is unloaded. Necessarily, this action of the boom and dipper in the stopping movements creates severe stresses and strains both upon the boom supporting means at the point of connection with the crane body, and upon the dipper stick or handle itself. At times the operator of the machine accidentally side-swipes a vehicle or bank or other obstacle, giving rise to additional severe tortional strains on the connections at the foot of the boom and the dipper stick and the dipper. In United States Patent No. 1,662,902 granted to L. A. Russell, there is provided a construction which is designed to relieve the boom from such hurtful tortional strains by absorbing the shocks through the provision of a dipper supporting boom construction wherein the body of the boom is mounted for turning movement relatively to the chute of the boom about an axis longitudinally of the boom, the body and chute members of the boom being maintained in their normal positions by resilient means such as springs. These springs are designed to absorb the shocks and stresses to which the boom and dipper stick may be subjected incident to their use in ordinary excavating operations.

The present invention relates to a modification of the construction described and claimed in the above mentioned patent, wherein the rotative body of the boom in that patent is replaced by a boom rigid in its entire length, so that there will be no turning of the boom body at any time. The boom body, however, is provided with a pair of collars between which is positioned a hearing which directly carries the dipper assembly, the bearing being turnable around the boom and serving as a connection for the dipper assembly with the boom; the bearing being positioned intermediate the dipper assembly and the boom. action of this bearing is to turn under the influence of tortional stresses imparted thereto through the operation of the dipper, this turning movement being opposed by cooperating springs adapted to absorb the shocks incident to such tortional strains and stresses.

The invention will be more readily understood by reference to the accompanying drawing, in which Figure 1 is a diagrammatic side view showing the shovel crane equipped with the constructional features embodied in this invention.

Figure 2 is an elevation of the boom of the present invention showing the constructional features applied thereto.

Figure 3 is a view taken along the sectional line 33 of Figure 2.

Figure 4 is a sectional view along the sectional line 44 of Figure 2, certain parts being omitted.

Figure 5 is a side elevation of the construction of Figure 4.

Figure 6 is a fragmentary view showing a somewhat different form of the invention as applied to a square boom.

Figure '7 is a View of the bearing member of Figure 6.

Figure 8 is a sectional view along the line 8--8 of Figure 6, certain parts being omitted.

Figure 9 is a side elevation of the form illustrated in Figure 8.

Referring more specifically to the drawing, the car or body of the crane is indicated 10, being provided with a traction support 11, the traction support being composed of endless traction members as is well known in the art, there being provided the usual swing body or turntable mounting intermediate the body 10 and the traction support 11. The shovel boom or boom element is designated at 12, the boom being rigidly supported by the boom foot 13.

The

The dipper assembly comprises the dipper 14 connected to the usual dipper stick 15 which is connected to the boom by instrumentalities comprising the features of novelty resident in this invention. The dipper assembly also comprises the usual saddle blocks 16 and 17, shown as straddling theboom 12, the pinions 18 and 19 for engaging the well known racks on the dipper stick, and the shipper drum 20. This boom assembly is carried on the shipper shaft 21 which passes through the offstanding arms 22 and 23 of a bearing member 24 which is mounted on the boom 12 between the collars 25 and 26, this bearing 24 being adapted to tend to turn around the boom when under the influence of the stresses and shocks above referred to occurring in the movements of the dipper when under actual conditions of service. Through these offstanding arms 22 and 23 there is also passed a shaft 27 upon which are mounted the cooperating springs 28 and 29, posi tioned between the oifstanding arms and between a member 30 secured to the boom. These springs will serve to resist the turning movement of the bearing 24 and will absorb the hurtful shocks above mentioned substantially completely so as to avoid possible injury to the boom.

It will be observed that while the boom may be constructed in two parts, one fitted within the other, the rivets 31 which secure the member 30 to the boom pass through both of the boom mem-- here so as to rigidly unite these members together and prohibit any turning movement of any portion of the boom itself; and to further strengthen this joint, the parts may be additionally welded together. The torsional shocks transmitted to the bearing member 24 will produce a movement of the bearing and the dipper assembly as indicated by the dotted lines in Figure 4, which movement is resisted by the springs 28 and 29 as above described.

As further illustrated, the boom is riveted to the boom foot 13 as indicated by the rivets 32 and is provided at its other end with the usual pulleys 33 over which the hoisting cables 34 are passed.

As illustrated in Figures 6 to 9 inclusive, the principles of this invention may be applied to a square boom as well as to a round boom. For this purpose, the round bearing 35 is made into two parts or sections, which are capable of being bolted together as shown at 36, the bearing 35 fitting over a round bearing member 35a, which is provided with the collars 3'7 and 38, and with the square projections 39 and 40 which are adapted totfit into the hollow boom and be riveted thereto as shown at 41 and 42 respectively. Otherwise the construction is entirely similar to that previously described, the oifstanding arms 43 and 44 of the bearing 35 receiving the shipper shaft 45, there being the member 46 riveted to the boom and encircling a shaft 4'7, to serve as a bearing member for cooperating springs 48 and 49, entirely similar to the springs 28 and 29, as above described.

It will thus be seen that by the present invention there is provided a boom entirely rigid throughout its length, and provided with a shock absorbing bearing connecting the dipper assembly with the boom which will eificiently prevent in a very simple manner transmission of hurtful shocks to the boom. It will be understood also that the details of the construction illustrated and specifically described above may be varied quite widely without departing from the inventive concept; and accordingly the herein described and illustrated form of the invention is to be regarded as typifying, but not limiting, the invention in the matter of these illustrated details. In fact, it will be apparent that many changes in these details can be readily made without departing from the principles upon which the invention is based. and it will be accordingly understood that it is intended and desired to embrace within the scope of this invention such modifications and changes as may be necessary to adapt it to varying conditions and uses.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States, is-

i. In a. crane construction of the class described, the combination with a crane body, of a boom construction including a foot member connected with the body and a boom body member mounted upon the foot member, together with a resilient bearing member mounted upon the boom body member, and a fore and aft and transversely swingable dipper stick reciprocably mounted thereon, said bearing member absorbing shocks or stresses created by sweeping and stopping movements of the dipper under actual conditions of service.

2. A boom structure for power shovels, 00111- prising in combination, a rigid boom, a dipper assembly therefor, a bearing member mounted on the boom and tending to turn thereupon, the bearing member having oif-standing arms at opposite sides of the boom, a pair of shafts passing through the offstanding arms, one of the shafts projecting beyond the arms and serving as the carrying shaft 1.

for the dipper assembly, and a pair of cooperating springs mounted on the other shaft between the arms, the springs acting to oppose turning of the bearing member thereby preventing transmission of harmful tortional shocks to the boom.

ROBERT J. DARRAH. 

